US2116840A - Gas burner - Google Patents

Description

H. C. LLOYD May 10, 1938.

GA BURNER Fi led June 11, 1935 2 sheets-sheet 1 l/l/ f l/ I Ill// 1/ IIIIIIIIIIIIIIIII INVENTQR. 7% M 7/ ATTORNEY5- May 10, 193224 H L D 2,116,840

was BU-RNER Filed June ll, 19:55 2 Sheets-Sheet 2 INVENTOR.

ATTORNEYS.

Patented May 10, I938 N-TED STATES PATENT OFFICE 11 Claims.

This invention relates to gas burners, and partlcularly to gas burners where the gas is supplied under pressure, and has for its general object a gas burner which is especially economical in oporation, producing maximum heat with the minimum amount of gas.

It further has for its object a gas burner in which the pressure of the gas is reduced during its passage to the burning area, to below atmosm pheric pressure and passed at low velocity through the burner to the burning area by what might be called the draw of the flame, and primary air at atmospheric prre is mixed with the gas during its passage through the burner below atmospheric pressure.

It further has for its object a gas burner in which the output of the ture of air and gas is many times greater compared with the input of the as, by reason of the air mixed at atmospheric pressure with the gas supplied under pressure, but reduced to below atmospheric pressure during its passage through the burner.

it further has for its object,.means for regulating the temperature developed and the draw of the flame by regulating the amount of primary air supplied to the gas below atmospheric pressure.

it further has for its object a gas burner by which has and air is mixed at atmospheric pres- 30 sure and is moved through the burner by the draw of the flame in contradistinction to being forced through the burner and the air drawn into the burner injector fashion to mix with the gas,

by the gas pressure, as in the Bunsen types of 35 burners.

In describing this invention, reference is bad to the accompag drawings in which like charactors designate corresponding parts in all the views.

Figure l is a verticalsectipnal view through one embo of this burner, the contiguous portion of the walls of a heater or a furnace being also shown.

Fl 2 is a sectional view on line 2-2, Fig- 45 We 1.

Figure 3 is a cross-sectional view through one of the expanding and mixing tubes.

in i is a View similar to Figure l of a slight ly diiierent ement of the invention.

The burner or apparatus comprises a. receiver for the gas from the supply pipe, a mixing chamber in free, open unobstructed or unrestricted communication with the receiver, and a second expansion chamber in free, open, unobstructed communication with the mixing chamber, these chambers, particularly the mixing chamber, having throughout the area of their walls numerous inlet openings for primary air at atmospheric pressure and the expansion chamber having an outlet at its end of sufllcient capacity to permit the free outlet of the mixture of expanded gas and air so that when the gas is ignited, the draw of the flame will move the gas andthe mixture of gas and air, which is below atmospheric pressure, upwardly through. the apparatus, permitting, the primary air to enter and mix with the gas. The expansion chamber may also be provided with primary air inlet openings. The gas or mixture is ignited in the' mixing chambers and partial combustion takes place in the mixing and expansion chambers, but full combustion takes place when the gas reaches the upper end,tip, or burning area. where the gas comes in contact with secondary air. This results in gradual flame propagation.

i designates the receiver for a gas under pressure, which may be supplied through a conduit 2 from a suitable supply of gas, as a gas main, the conduit 2 having a suitable control valve 3 therein. As here shown, the receiver is provided with upper and lower chambers i, 5, separated by a perforated bafiie plate 3, the receiver being shown as including upper and lower sections,'the lower section i of which constitutes a. base, and the upper section a dome threaded on the base.

The baille plate 5 is located between the sections. The inlet pipe 2 opens into the base or the chamber 5 thereof under the baiile plate 6.

ii and t) designate the primary mixing and the exnslon chambers. The mixing chambers 8 are in free, open, unobstructed or unrestricted I communication with the receiver i;or the chemher 6 thereof, and also with the expansion chamher 9. The mixing chambers, as here shown, are in the form of a plurality of upright tubes perforated throughout their areas for the inlet of primary air, the tubes communicating with the chamber i of the receiver through the top thereof and with the expansion" chamber 9 through the bottom thereof. Each of these tubes is approximately one-half inch in diameter, and provided throughout its area with air inlets ill of approximately one-sixteenth inch in diameter. I

The baflle plate 6 is provided with perforations ii of approximately the same diameter as the bores oi. the tubes of the mixing chambers. The burning point, tip-or area I2 is at the upper end of the expansion chamber. A suitable spreader i3. is mounted above the burning point or area. The outlet [4 at the upper end of the expansion chamber is of suflicient capacity to permit the moving of'the expanded or expanding'mixture without back pressure. when the burner is ignited, the movementof the expanded or expanding gas is effected or facilitated by the draw of the flame.

The output of the mixture is about forty-two times as great as the input of the gas, and owing to the large outlet and the draw of the flame, the mixture is moved through the tubes 8 and expanslon chamber 9 below atmospheric pressure, permitting primary air to enter at atmospheric pressure through the holes iii and intimately mix with the expanding gas passing therethrough.

5 This construction and method is diametrically opposite that of burners working on the Bunsen burner or injector principle.

The expansion chamber is also formed with air I inlet'openings i5 and the flangelb at the tip of the burning area of the expansion chamber 9 is also preferably formed with annular series of air openings ii for secondary air.

The primary air may be supplied to the tubes from the air within the wall it of the heater or furnace in which the burner is installed but preferably, as the air is exhausted from within. the furnace, due to the burning. Primary air is supplied from the outside of the furnace. As here shown, the primary air is supplied through an annular conduit 28 around the base 'i and having outlet openings 2i in its upper side, the conduit 20 communicating with the outer air through a supply pipe 22 which communicates with the air outside the heater, preferably through the opening in what is ordinarily the ashpit door 23 of the furnace, which opening is usually controlled by a damper.

In the installation shown in Figure 1, the damper is removed in order not to obstruct the passage of air through the conduit 22. The primary air is here shown as controlled by a valve, damper or register 25 mounted to rotate on the upper wall of the'primary air conduit 2t and havingppenings 25 arranged to be moved into and out of alinement with the openings 28 to open or close them, more or less. This damper, valve or register 2d may be operated'by hand but is preferably thermostatically operated. As the automatic thermostatic operation of a damper is well known, further description is thought to be unnecessary.

In operation, the gas is supplied through the pipe 2 under pressure, and this pressure may be regulated for the particular installation or varied to suit changing conditions by means of the valve 3. The gas flows into the chamber 5 of the receiver and is distributed by the baflle plate 6 so that it flows upward through the holes I I thereof and is distributed substantially equally into the lower ends of the tubes 8. As these tubes are unobstructed, the gas passes upwardly therethrough being drawn up through the same by the draw of the flame at the burning area ii. The gas expands during its passage through the tubes 8 and while in the expansion chamber 9, and hence, the pressure thereof is reduced. The tubes 8'and the number and size of holes therein and the size or capacity of the expansion chamber il-are so proportioned to the burning area that 00 the pressure of the gas is reduced to below atmospheric pressure, and moves without velocity under pressure of the gas, the movement of the gas being due to the expansion of the gas and the draw of the flame. As the interior of the tubes 8 and expansion chamber 9 are below atmospheric pressure, the primary air will enter through the holes in the tubest and evenly and intimately mix with the gas throughout the entire body of the gas. Further mixing of the primary air with the gas in the expansion chamber 8 is through the series of holes i5. jIhe primary air is supplied through the conduit 20 and the damper 24 The gas is ignited in the tubes by a pilot light at Land hence partial combustion'takes place orthe flame begins to propagate before the mixture reaches the tip or burning area of the' burner. With these holes H, 25 fully open, a; maximum amount of air mixes with a given amount of gas below atmospheric pressure pro:- ducing a greater output at the opening i4 and a hotter flame. To reduce the temperature, the damper 24 is operated in any suitable manner to partly close the holes 2|, thus cutting down the amount of primary air mixing with the gas in the tubes 8 at the same time cutting down the flame and hence reducing the draw of the flame, and the velocity of the mixture through the apparatus, or automatically cutting down the amount of the mixture, and hence cutting down the draw of the flame and reducing the temperature. Thus, as the pressure of the gas is below atmospheric pressure, the temperature and the amount of gas consumed is controlled by the primary air, and thus the balance and proportion of the primary air and gas automatically maintained.

As seen in Figure 4, provision is made for heating the primary air before entering the tubes 8, and in this construction, the damper 30 on the ashpit door is not removed but is utilized to control the flow of primary air through the interior of the furnace. In order to preheat the primary air, a jacket M is provided around the mixing and expansion chambers 8 and 9 and a partition or bame 32 provided extending from the rim of the expansion chamber, that is, fromthe burning area, to the wall of the heater or furnace. The jacket 3i being closed at its bottom and open at its top,the air enters through the ashpit door, passes upwardly, as indicated by the arrows, around the jacket 3!, against the partition 32, then downwardly into the jacket and through the holes of the tubes 8. In starting the burner, it has been found desirable to have more primary air fed to the tubes 8 than ordinarily would -pass, after the heater is'started. In order to provide for suflicient primary air when the burner is cold at starting and to keep the tubes and expansion chamber cool, the jacket is formed with perforations 33 in the wall thereof around the tubes 8, and these perforations 33 are opened or closed, more or less, by means of a damper or register 34 surrounding the jacket and having openings movable into and out of register with the openings 33. This damper 3| is initially adjusted to the particular installation.

The operation of the form shown in Figure 4, is substantially the same as that shown in Figure 1, with the exception that heated secondary air may be supplied to the flame or the burning area through the series of holes 31 from the portion ceiving an ignitable gas, mixing and expansion chambers, the former chamber having free, open, unrestricted inlet and outlet passages communicating with the receiver and expansion chamber respectively, and the expansion chamber having an outlet, the mixing chamber comprising a plurality of elongated passages of relatively smallcross-sectional' area, and each of said passages the unrestricted mixing chamber passages being of suflicient size and number to permit the gas "to flow therethrough witha relatively low velocity, and to maintain a pressure in the mixing chamber below atmospheric pressure, all whereby a progressive intimate mixture of air with the gas is effected intermediate the receiver and the expansion chamber outlet, affording complete combustion at the expansion chamber outlet and an intensely hot flame.

2. Apparatus asclaimed in claim 1, wherein means is provided for regulating the amount of primary air admitted through the primary air inlet openings which communicate with the passages of the mixing chamber.

3. A device as claimed in claim 1, wherein means is provided for preheating the primary air before it is admitted into the mixing chamber to mix with the gas. I

4. A burner comprising a receiver for receiving an ignitable gaseous fuel, an expansion chamber spaced above said receiver and having an outlet of relatively large size at its upper end, and also having a plurality of perforations arranged in the sides thereof adapted to communicate with a source of air at atmospheric pressure, a plurality of unrestricted tubes comrnunicating at their upper and lower ends respectively with the expansion chamber and re vceiver, each of said tubes being of relatively,

small cross-sectional area and having a plurality of axially and circumferentially spaced perforations therein adapted to communicate'with a source of primary air at atmospheric pressure, the combined cross-sectional areas of the tubes being sufficient to permit the gaseous fuel to pass from the receiver to the expansion chamher at relatively low velocity and at a pressure below atmospheric, responsive to the free expansion of the gaseous fuel and the draw of the flame, while primary air is progressively and intimately mixed therewith in an amount sufflcient to ultimately support primary combustionadjacent to the upper ends of the tubes, and the air which is adapted to be admitted into the expansion chamber through the expansion chamber perforations aforesaid being adapted to produce secondary combustion in the expansion chamber, whereby to eflect complete combustion at the expansion chamber outlet.

i 5. -A gas burner comprising a receiver for receivlng an ignitable'gas, an expansion chamber spaced above saidreceiver, means establishing communication between said receiver and expansion, chamber for directing the gas from the former to the latter at relatively low velocity, and for dividing the gas into a plurality of individual columns of relatively small cross-sectional area, said means having provision for progressively exposing each columnof gas to a source of primary air at atmospheric pressure to be admixed therewith while the gas is passing from the receiverto the expansion chamber, and said expansion chamber having an outlet of rel atively large size at its upper end and of sufllcient capacity to. permit the gas pressure to be and thereby insure an intimate mixture of the air with the gas prior to combustion at the expansion chamber outlet.

6. The combination with a, burner as claimed in claim 5, of means for excluding air from the burner in excess of that required to effect complete combustion at the expansion chamber outlet.

'1. The combination with a burner as claimed in claim 5, of means for excluding air from the let, said means including a perforated baflle extending laterally from the burner.

8. The combination with a burner as claimed in claim 5, of means for excluding air from the burner in excess of that required to effect complete combustion at the expansion chamber outlet, said means including a perforated baiiie extending laterally from the burner, disposed adjacent to the burner outlet, and which is adapted to substantially close the space between the burner and the furnace wall when the burner is mounted in a furnace.

9. The combination with a burner as claimed in claim 5, of means for excluding air from the burner in excess of that required to effect complete combustion at the expansion chamber outlet, said means including a perforated baiile extending laterally from the burner disposed ad-.

jacent to the burner outlet, which is adapted to substantially close the space between the burner and the furnace when the burner is mounted in a furnace, and a spreader disposed above the expansion chamber outlet and in spaced relation to the baille aforesaid for directing the flame laterally towards the furnace wall.

10. A device of the class described, comprising a receiving chamber adapted to receives. gaseous fuel, an expansion chamber having an outlet, means for conducting the gaseous fuel from the receiver to the expansion chamber at a relatively low velocity, while permitting the gaseous fuel to expand below atmospheric pressure, said means having provision for progressively and intimately mixing a combustion supporting fluid with the gaseous fuel in an amount sufficient to ultimately produce primary combustion but less than required to produce complete combustion, and meansfor producing secondary combustion in the expansion chamber while excluding excess combustion supporting fluid beyond the.

- but less than, required to produce completejcombustion, and means for producing secondary combustion in the expansion chamber whileexcluding excess combustion supporting fluid beyond the amount required to support complete combustion at the expansion chamber outlet, said last named means including means for producing limited tertiary combustion adjacent to the expansion chamber outlet.

. HARRY C. LLOYD.

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